KWS Manufacturing

Load Out System for Wastewater Grit and Screenings Waterloo, ON WWTP

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Plant Name and Location

Waterloo WWTP
Waterloo, ON

End User or Owner

City of Waterloo
Waterloo, ON

Consulting Engineer

Markham , ON L3T 7W3


Malfar Mechanical Inc.
Woodbridge, ON L4L 7Y3

General Description

The City of Waterloo was expanding their Environmental facilities due to additional demand on the current facilities. A new system was required to combine and convey dewatered screenings and grit from bar screens and grit classifiers to a loading area where the residuals could be transferred into dumpsters. The complete system was automatic requiring no operator intervention. The residuals from the headworks part of the plant (dewatered screenings and grit) are very odorous and can pose a health risk to operations staff. Furthermore, the area is deemed high risk of explosion and equipment must be designated explosion proof (i.e. NEMA 7/9 electrical rating). KWS designed a conveyance system that received material from one to three bar screens and one to two grit classifiers and conveyed the combined residuals to dumpsters. The system design was redundant and flexible allowing for the sequencing of conveyors and contoured slide gates to be automatic. Residuals could be loaded to one of two dumpsters and loaded evenly along the length of each dumpster.

Design Parameters

  1. Type of Material: Dewatered Screenings and Grit
  2. Material Density: 900 to 1,400 kg. per cubic meter
  3. Solids, % by weight: 18 to 20-percent
  4. Capacity: 6.2 wet cubic meters per hour

KWS Advantages

KWS provided a complete system for conveying residuals from the discharge of the bar screens and grit classifiers to the dumpsters. The scope of supply included design as well as the manufacture and delivery of all components and assemblies for the conveying system. The KWS system included chutes and support structures, screw conveyors, motion sensors, level sensors, overload protection and explosion proof control panels.

KWS supported the installation, commissioning and training by providing a qualified and registered Professional Engineer familiar with the project, design requirements and equipment delivered.

Special Features

KWS provided contour type gates which require less headroom and provide better sealing of residuals with high levels of free liquid. Since grit is extremely abrasive, the conveyor spirals are extra-tough 340-BHN hardness to extend the spiral life. The system included level sensors that were located adjacent each loading conveyor gate to allow for automatic control of the distribution of grit and screenings in the dumpsters. A high level alarm to SCADA was provided so the system would automatically switch from one dumpster to another and shut down when both dumpsters were full.


"The system works as envisioned by the Design Consultant and we appreciated the input from KWS at each step of the project from concept to final commissioning."

Joe Carrabetta – Project Manager, Malfar Mechanical


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